UES 104 Module 1 Taxonomy and Biological Classification PDF

Module 1 Taxonomy and Biological Classification Chandrashekhar Azad Vishwakarma, PhD Assistant Professor Department of Natural and Applied Sciences, TERI School of Advanced Studies  Taxonomy Biologists want to better...

Module 1 Taxonomy and Biological Classification Chandrashekhar Azad Vishwakarma, PhD Assistant Professor Department of Natural and Applied Sciences, TERI School of Advanced Studies  Taxonomy Biologists want to better understand organisms so they organize them. One tool that they use to do this is classification—the grouping of objects or information based on similarities. Taxonomy is the branch of biology that groups and names organisms based on studies of their different characteristics. The term is derived from the Greek taxis (“arrangement”) and nomos (“law”). Taxonomy is, therefore, the methodology and principles of systematic botany and zoology and sets up arrangements of the kinds of plants and animals in hierarchies of superior and subordinate groups. Biologists who study taxonomy are called taxonomists.  Taxonomy Homo sapiens Homo because of our large brain and upright posture. sapiens because of our intelligence and ability to speak.  Why Classify? “Watch out—there’s a bear behind that rock! OR “Watch out--there is a large, furry, four-legged creature with long claws, a big mouth set in a short, stout muzzle, attached to a round head containing small eyes and short triangular ears behind that rock!” Why Classify? Q. What is the largest wild felid (cat) in the United States? Mountain Lion Cougar Panther Painter Puma Catamount Why Classify? All of the above Puma concolor  Why Classify? Need for the classification The number of known and described species ranges between 1.7 to 1.8 million. These plants and animals worldwide are known in their area by their local names. Hence there is a need to standardise the naming of living organisms required and the process known as nomenclature. Scientists established a procedure to assign a Source: https://www.iapt- scientific name to each organism which is accepted taxon.org/nomen/main.php worldwide. For Plant: International Code for Botanical Nomenclature (ICBN) For Animal: International Code for Zoological Source: https://www.iczn.org/ Nomenclature (ICZN) They also ensure that these name can not been used for any other known organism. Why Classify? Need for the classification ALL ORGANISMS: TOTAL SPECIES 1,413,000 Insects 751,000 Other Animals 281,000 Higher Plants Viruses 248,000 1,000 Prokaryotes Protozoa (Eubacteria & 30,800 Algae Archaebacteria) 26,900 4,800 Fungi 69,000 Source: https://counterbalance.org/cq-via/lifeo-frame.html  Binomial Nomenclature Biologists follow universally accepted principles to provide scientific names to known organisms. Each name has two components: Generic name Specific epithet This system of providing a name with two components is called Binomial nomenclature. Carolus Linnaeus gave this naming system and it is being used by biologists all over the world.  Binomial Nomenclature Linnaeus described and named > 6,000 animals and >4,000 plants using Latin. Taxonomists are required to use Latin because the language is no longer used in conversation and, therefore, does not change. In this system: The first word identifies the genus of the organism. A genus (genera-plural) consists of a group of similar species. The second word, which sometimes describes a characteristic of the organism, is called the specific epithet. The first letter of the genus name is Uppercase, but the first letter of the specific epithet is lowercase. Scientific names should be italicized in print and underlined when handwritten. The name of the author appears after a specific epithet and is written in an abbreviated form Example: Mangifera indica Linn. This indicates that this species was first described by Linnaeus.  Binomial Nomenclature Homo sapiens is sapient (wise or aware) man. But, what is Cocos nucifera? the coconut tree nuc = nut + fera = carrying Binomials are unique to eliminate confusion that often arises from regional differences in common names For example, what is a skipjack? In Guam, a skipjack is a young trevally In Hawaii, a skipjack is a tuna Caranx melampygus Kasuwonus pelamis (bluefin jack or trevally) (Skipjack Tuna) Binomial Nomenclature carp Source: https://keralapscadda.blogspot.com/2016/07/list-of-scientific-names-of-common.html  History of classification There is a need to study all the organisms and it can not be possible without categorise or grouping them, this process is called classification. The classification is the process by which anything is grouped into convenient categories. Based on the characteristics, all living organisms are classified into different taxa. This process of classification is Taxonomy. Some key points for taxonomic studies: – External and internal structure Source: https://www.teachthis.com.au/products/external- – Structure of cell features-of-animals – Development process – Ecological information Hence the process of taxonomy is based on: – Characterization – Identification – Nomenclature  History of classification Over the centuries, several classification schemes have been proposed All are hierarchical—reflecting different degrees of similarity among organisms, i.e., similar organisms are placed together in the same taxon Among them, the first attempt was made more than 2,000 years ago by the Greek philosopher Aristotle. He is also known as the “Father of Zoology”. He classified the animals into two main groups: – Anaima (Invertebrate): lacking red blood Source: https://superbloov.life/product_details/42677228.html cells – Enaima (vertebrates): having red blood cells And classified plants based on stem and life duration into herbs, shrubs and trees. Certain animals lived in two different habitats like amphibians and its could not explain by this classification.  History of classification Modern classification dates from mid-eighteenth century Carolus Linnaeus (1707–1778) is considered the Father of Modern Taxonomic Classification Linnaeus was a Swedish medical student studying in Belgium. He classified and listed the plant and animal species in his book in 1758. He listed over 4400 animal species that are known to him in his book “Systema Naturae”. Similarly, he named over 8000 species of plants in his book “Species Plantarum”. Linnaeus used an organism’s morphology (form and structure), to categorize it. His classification system is still being used today. His system allowed organisms to be grouped with Carolus Linnaeus similar organisms.  Taxonomic Categories Since the classification is a step-by- More specific step process and it involves a hierarchy of steps representing a rank or category. This taxonomic arrangement is called as taxonomic category. More general All the categories together constitute Fig: Pyramid of Taxon the taxonomic hierarchy. Each category is referred as a unit of classification, termed as taxon (plural, taxa). Each rank of taxon represents a unit of classification. Organisms are ranked in taxa that range from having very broad characteristics to very specific ones.  Taxonomic Hierarchy Mnemonic Kingdom kings Phylum play Class cards Order on Family fine Genus green Specific epithet (species) sofas These are the common categories of all known organisms. There is a need to understand, how the organism places in various categories. The basic requirement is the knowledge of the characters of an individual or group of organisms.  Taxonomic Hierarchy Species Group of individual organisms with fundamental similarities as a species. The species can be distinguished from other closely related species based on the distinct morphological differences. It refers to a group of organisms that are Ursus maritimus Solanum nigraum similar in shape, form, and reproductive features. According to studies, there are around 8.7 million different species of living organisms on Earth. A lot of living organisms are yet to be discovered and categorized. Species can be further divided into sub- Solanum lycopersicum Ursus arctos horribilis species.  Taxonomic Hierarchy Genus (plural: genera) Genus comprises a group of related species that has more common Panthera pardus characters than other genera. Panthera leo It is the aggregate of closely related species. It is the first part of an organism’s scientific name using binomial Panthera tigris nomenclature; the second part is the species name. An organism’s scientific name is always italicized, and the genus name is capitalized while the species name is not. Brassica oleracea var. Brassica camprestis  Taxonomic Hierarchy Family Family is the group of related genera with fewer similarities as compared to genus and species. Families are characterized based on both vegetative and reproductive features of plant species. Example: Among plants, the genus Solanum, Petunia and Datura are placed in a family Solanaceae. Among animals, the genus Panthera comprising lion, tiger, leopard is put along with genus Felis (cats) in the family Felidae.  Taxonomic Hierarchy Order Order and other higher taxonomic categories are identified based on the Fig: Floral aggregates of characters. characters of family Solanaceae Order is the assemblage of families which exhibit a few similar characteristics. Example: Plant families like Convolvulaceae, Solanaceae are included in the order Polymoniales mainly based on the floral characters. The animal order, Carnivora, includes families like Felidae and Canidae. Fig: Floral characters of family Convolvulaceae  Taxonomic Hierarchy Class This category includes related orders. Order is the assemblage of families which exhibit a few similar characteristics. Example: Order Primata comprising monkey, gorilla and gibbon is placed in class Mammalia along with order Carnivora which includes animals like tiger, cat and dog. Phylum (pl. phyla) The classes comprising animals like fishes, amphibians, reptiles, birds along with mammals constitute the next higher category i.e. Phylum. The categorization is based features like presence of notochord and dorsal hollow neural system and are included in phylum Chordata. Whereas in plants, classes with similar characteristics are assigned to a higher category called Division. Kingdom All animals from various phyla are assigned to the highest category called Kingdom Animalia. On the other hand, the Kingdom Plantae comprises all plants from various division.  Taxonomic Hierarchy Classification Hierarchy of animals Taxonomic Hierarchy Classification of Modern Humans  Taxonomic Hierarchy Classification of cheetah  Taxonomic Hierarchy Source: https://iowaagliteracy.wordpress.com/2020/02/26/science-101-plant-classification/  Classification System The classification system is based on the features of organisms and arranging them into different groups. The classification system aims to establish the relationship among different organisms and to know about their evolution. There are three types of classification systems. Classification System Artificial Natural Phylogenetic Classification Classification Classification  Classification System Artificial System of Classification It is the earliest classification system which remained dominant from 300 BC to 1830. In this classification, some arbitrary at least easily observable characters were used and these characters were called artificial. This type of classification is based on habitat and external features i.e. morphology or the numeric number of sex organs. Examples: Theophrastus classified the plants into four groups based on their habit: herbs, undershrubs, shrubs and trees. The sexual system of Linnaeus is a good example of artificial classification, which uses only one attribute i.e. the number of stamens for grouping plants into 24 Classes.  Classification System Demerit of Artificial System It could not be accepted as: It was based on superficial characteristics. It did not take into account the relationship between the different organisms. Organisms belonging to different groups were placed together. e.g., birds and bats were placed in the same group due to their ability to flight.  Classification System Natural System of Classification Bentham and Hooker proposed (between 1862 to 1883) this system of classification and published in Genera Plantarum. This classification is based on overall resemblances. This system of classification is not only based on the external features but also the internal features like Ultrastructure, Anatomy, Embryology and Physiochemistry. Organisms show close resemblance because the are descended from a common ancestor. Thus the closely related species should naturally be grouped together and this is called as Natural Source: https://www.mrgscience.com/topic-53-classification-of- classification. biodiversity.html Example: Birds, reptiles, and mammals are placed in different groups based on multiple features.  Classification System Merit of Natural Classification System It is better than the artificial system of classification as: It does not consider habit and habitat as characteristics for classifying organisms. It helped the related organisms to be placed in one group only. The system prevents placing together the non-related organisms. The system indicates phylogenetic relationships and the origin of different taxa. Demerit of Natural Classification System Source: https://www.mrgscience.com/topic-53-classification-of- biodiversity.html It does not consider habit and habitat as characteristics for classification.  Classification System Phylogenetic System of Classification This classification system was proposed by Engler, Prantle & Hutchinson (1886). It is based on the evolutionary and genetic relationship of the organisms. The evolutionary history of a group of genetically related organisms, called Phylogeny. It includes ancestor species and Fig: Phylogenetic Tree (Source: https://www.ck12.org/section/phylogenetic-classification/) descendant species. A phylogeny is usually represented by a tree diagram called a phylogenetic tree. Darwin’s “Tree of Life” was the early example of a phylogenetic tree. The tree shows how species evolved through time from the bottom of the tree to the top. Source: https://www.geeksforgeeks.org/human-evolution-stages/  Classification System Fig: Phylogenetic tree depicting the relationships between gorillas, chimpanzees, humans, and human-like relatives (stem-group hominins) (Source: https://www.geeksforgeeks.org/human-evolution-stages/ )  Classification System Source: https://www.gf5tees.com/products/charles- darwin-w-tree-of-life-sketch-mens-cotton-poly-tee  Classification System Phylogenetic System of Classification Cladistics The method of adding information into the phylogenetic tree is called cladistics. This is a method of comparing traits in related species to determine ancestor-descendant relationships. Cladistics come from the word clade. Clade is a group of organisms that includes an ancestor species and all of its descendants. The diagram showing evolutionary relationships within one or more clades is called a cladogram.  Classification System Fig: The cladogram claasifies mamals, reptiles and birds in clades based on their evolutionary relationships (Source: https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK- 12)/05%3A_Evolution/5.12%3A_Phylogenetic_Classification ) The cladogram represents the mammal and reptile clades. The reptile clade includes birds. It shows that birds evolved from reptiles. Linnaeus classified mammals, reptiles, and birds in separate classes.  Five Kingdom System Initially, living organisms were divided into two kingdoms i.e. Animalia and Plantae. Currently, all living organism divide into five kingdoms: Monera (bacteria) Protista Fungi Plantae Animalia This kingdom system coexist with two main divisions: Prokaryotae (bacteria etc.) Eukaryotae (animals, plants, fungi Source: https://science.howstuffworks.com/life/cellular- and protists) microscopic/prokaryotic-vs-eukaryotic-cells.htm The prokaryotes are further divided into two domains, the Bacteria and the Archaea which are different from the Eukaryota or eukaryotes (three domain of life).  Five Kingdom System Living organism Plantae Animalia Two kingdoms Living organism Monera Protista Fungi Plantae Animalia Five kingdoms Prokaryotae Bacteria Archaea Eukaryotae Three domains Three domain system classification was given by Carl Woese in 1990. Dr. Woese proposes new category of classification of life above Kingdom. The domain classification helps to understand the relationship within five kingdom system.  Five Kingdom System Classification Proposed by Classification type Two Kingdom Linnaeus in 1758 Plantae Animalia Three Kingdom Ernst Haeckel in Protista Plantae Animalia 1860s (BGA, protozoa etc.) Four Kingdom Lynn Margulis and Monera Protista Metaphyta Metazoa Copeland in 1956 Five Kingdom R.H. Whittaker in Monera Protista Fungi Plantae Animalia 1969 Six Kingdom Carl Woese in 1990 Archaebact Eubacteria Protista Fungi Plantae Animalia eria Fig: Six-Kingdom Classification System  Five Kingdom System Five kingdom system were proposed based on levels of organization and on type of organization as evolved in relation to three principal means of nutrition-photosynthesis, absorption and ingestion. The five kingdom classifications were proposed by Robert Harding Whittaker (1969). This classification is based on: Complexity of cell structure Source: https://www.careerpower.in/school/biology/five-kingdom- Complexity of organism’s body classification Mode of obtaining nutrition Reproduction Phylogenetic relationship In this classification, the sub-division of old two-kingdom classification have not been changed. This arrangement depicts the phylogeny of various life styles better. Fig: Phylogenetic relation of five kingdom Five Kingdom System